Effect of nitrogen additives on flame retardant action of tributyl phosphate: Phosphorus-nitrogen synergism

The effects of three nitrogen additives (urea, guanidine carbonate, and melamine formaldehyde) on the flame retardant action of cotton cellulose treated with tributyl phosphate (TBP) were investigated in this research. The limiting oxygen index (LOI) of treated cotton cellulose clearly revealed the synergistic interactions of TBP and nitrogen compounds. The Kissinger method was used to evaluate the kinetics of thermal decomposition on treated cellulose. The results show that adding nitrogen additives increases the activation energy at a higher degree of degradation, thus indicating better thermal stability at higher temperatures. Scanning electron microscope pictures of chars formed after a LOI test show the formation of protective polymeric coatings on char surfaces. Evaluating char surfaces using attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggests that these coatings are composed of species containing phosphorus-nitrogen-oxygen. Possible chemical interactions of phosphorus and nitrogen compounds during the burning process and the formation of a protective coating could be the reason for the observed synergism. Potential reaction pathways contributing to the formation of this protective polymeric coating have also been proposed.     

Toxic action and antibiotic in the chemostat: permanence and extinction of a model with functional response

A system of periodic coefficients functional differential equations is used to model the single microorganism in the chemostat environment with a periodic nutrient and antibiotic input. Furthermore, the total toxic action on the microorganism expressed by an integral term is considered in our system. Based on the technique of analysis, we obtain sufficient conditions which guarantee the permanence of the system and extinction of the microorganism.      

氢氧化镧钠米线对多倍斯伏安响应的增敏作用及其应用

氢氧化镧钠米线修饰碳糊电极对多倍斯伏安响应有明显的增敏作用,其特征是多倍斯一对氧化还原峰的峰电流增大和峰电位差减小。这种增敏作用是由于氢氧化镧钠米线修饰电极有效面积的增大以及氢氧化镧钠米线与多倍斯间的化学作用。基于多倍斯在氢氧化镧钠米线修饰碳糊电极上灵敏的氧化峰,用线性扫描伏安法测定多倍斯,线性范围是3.0×10^-10～1.0×10^-8 mol·L^-1,检测限达5×10^-11mol·L^-1。     

表面修饰纳米二氧化硅及其与聚合物的作用

本文综述了近几年国内外对纳米二氧化硅的表面化学修饰及其在聚合物基纳米复合材料中与基体作用方式的研究工作。对纳米SiO₂进行表面修饰可以改善纳米颗粒与聚合物基体间的亲和性,同时可以使纳米SiO₂表面功能化,有利于SiO₂与聚合物基体间形成强的结合力。纳米SiO₂与聚合物基体间可以以吸附力、氢键、共价键等方式结合,不同的结合方式对材料性能也会产生不同程度的影响。     

Structural and biological behaviors of some nonionic Schiff-base amphiphiles and their Cu(II) and Fe(III) metal complexes

Novel series of nonionic Schiff bases was synthesized and characterized using microelemental analysis, FTIR and (1)H NMR spectra. These Schiff bases and their complexes with Cu and Fe have been evaluated for their antibacterial activity against bacterial species such as Staphylococcus aureus, Pseudomonas aureus, Candida albi, Bacillus subtilis and Escherichia coli and their fungicidal activity against Aspcrgillus niger and Aspcrgillus flavus. The results of the biocidal activities showed high potent action of the synthesized Schiff bases towards both bacteria and fungi. Furthermore, complexation of these Schiff bases by Cu(II) and Fe(III) show the metal complexes to be more antibacterial and antifungal than the Schiff bases. The results were correlated to the surface activity and the transition metal type. The mode of action of these complexes was discussed.     

Cellular Mechanistic Considerations on Cytotoxic Mode of Action of Phosphino Ru(II) and Ir(III) Complexes

Two piano-stool ruthenium(II) complexes Ru(η⁶-p-cymene)Cl₂PPh₂CH₂OH ( RuPOH ) and Ru(η⁶-p-cymene)Cl₂P(p-OCH₃Ph)₂CH₂OH ( RuMPOH ) and two half-sandwich iridium(III) complexes Ir(η ⁵-Cp*)Cl₂PPh₂CH₂OH ( IrPOH ) and Ir(η ⁵-Cp*)Cl₂P(p-OCH₃Ph)₂CH₂OH ( IrMPOH ) have been studied in terms of potential anticancer activity on previously selected cell line (human lung adenocarcinoma). Based on experimental results obtained in monoculture in vitro model mechanistic considerations on the possible cellular modes of action have been carried out. ICP-MS analysis revealed the higher cellular uptake for less hydrophobic Ir(III) complexes in comparison to the corresponding Ru(II) compounds. Cytometric analysis showed a predominance of apoptosis over the other types of cell death for all complexes. The apoptotic pathway was confirmed by a decrease in mitochondrial membrane potential and the activation of caspases-3/9 for both Ru(II) and Ir(III) complexes. It was concluded that in the case of Ru(II) complexes the intense ROS generation is mainly responsible for the resulting cytotoxicity. The corresponding Ir(III) complexes trigger simultaneously at least three different cytotoxic pathways i. e., depletion of mitochondrial potential, activation of caspases-dependent apoptosis, and ROS-associated oxidation. Thus, it can be assumed that the final accumulation of toxic effects over time via parallel activation of different pathways results in the highest cytotoxicity in vitro exhibited by Ir(III) complexes when compared with Ru(II) complexes.     

咪唑改性氧化石墨烯对阻燃环氧固化动力学的促进作用

讨论了添加量为1%(Per hundreds of resin)的咪唑改性的氧化石墨烯(GO-IPDI-MZ)对磷质量分数为1.5%的环氧树脂体系(1.5P-D-U-EMI)固化的影响.差示扫描量热法(DSC)研究结果表明,当GO-IPDI-MZ添加量为1%时不会改变1.5P-D-U-EMI的非等温自催化固化反应特征.添加1%GO-IPDI-MZ的磷质量分数为1.5%的环氧树脂(1.5P-D-GOM-1)的固化起始温度(Tonset)和峰顶温度(Tp)均比1.5P-D-U-EMI体系低,而总的固化热(ΔH)比1.5P-D-U-EMI体系高.说明GO-IPDI-MZ添加量为1%时,对环氧体系起到一定的促进固化和共固化作用.等温DSC分析表明,在固化反应后期,体系出现了玻璃化转变现象,在此阶段,含扩散控制因子的Kamal模型预测结果与实验结果吻合较好.GO-IPDI-MZ的加入使固化反应相对均匀地进行,对固化反应会产生促进和共固化作用.     

好氧颗粒污泥中凝胶型聚多糖的特性研究进展

凝胶型聚多糖(PS)是好氧颗粒污泥(AGS)中重要的结构性物质,具有稳定性强、可生化性低、交联度高等特点。鉴于AGS技术广阔的应用前景与"多糖机制"的最新突破,本文首先介绍了主要胞外聚合物(EPS)的含量范围与空间分布,重点综述了以颗粒体多糖(Granulan)与类海藻酸(ALE)为代表的凝胶型PS的化学组成、可能来源与结构性功能,并指出有针对性地开展分子动力学研究与微生物基因测序是该领域研究的发展方向。     

Impulsive Tension of Hexane and Glycerol under Shock‐Wave Loading

The strength of hexane and glycerol was measured under impulsive tension produced by interaction of a triangular compression pulse with a free surface. The tests were performed for strain rates of 10⁴–10⁵ sec^–1. It is established that the strength of hexane is equal to 14 MPa and does not depend on the strain rate, whereas the strength of glycerol increases from 57 to 142 MPa with an order of magnitude increase in the strain rate. The possibility of using the model of homogeneous nucleation to interpret the data obtained is discussed.